Echo canceling apparatus, telephone set using the same, and echo canceling method

Providing echo canceling apparatus, telephone set using the same and an echo canceling method that do not require transmission/reception sound detection and are resistant to environmental noise.Echo canceling apparatus according to the invention includes a calculator 4 for subtracting a pseudo-echo signal pec generated from a reception sound signal from an echo signal ec that is based on an echo generated when the reception sound that is based on the reception sound signal is reflected on a reflective body such as a wall thereby outputting a residual echo signal rec. The echo canceling apparatus further includes a residual echo detector 12 for estimating a residual echo volume by detecting sign inversion of the echo signal ec and the residual echo signal rec and their amplitude values. It is thus possible to compare between the positive and negative signs of the input/output signal of the calculator 4 without using the transmission/reception sound detection to detect the generation of a pseudo-echo signal thereby accurately estimating the residual echo volume.